Method of synthesis of hafnium nitrate for HfO2 thin film deposition via ALCVD process

摘要

A method of preparing a hafnium nitrate thin film includes placing phosphorus pentoxide in a first vessel; connecting the first vessel to a second vessel containing hafnium tetrachloride; cooling the second vessel with liquid nitrogen; dropping fuming nitric acid into the first vessel producing N₂O₅ gas; allowing the N₂O₅ gas to enter the second vessel; heating the first vessel until the reaction is substantially complete; disconnecting the two vessels; removing the second vessel from the liquid nitrogen bath; heating the second vessel; refluxing the contents of the second vessel; drying the compound in the second vessel by dynamic pumping; purifying the compound in the second vessel by sublimation to form Hf(NO₃)₄, and heating the Hf(NO₃)₄ to produce HfO₂ for use in an ALCVD process.